That was just last week, but it probably seems like the good ol' days to Cowboys fans now that their team has a real concern that could affect the entire 2014 season.

Linebacker Sean Lee could be out for the year after tearing a ligament in his left knee Tuesday, the first day of off-season practice.

During the 11-on-11 portion of practice, Lee's left leg slid out from under him, causing rookie guard Zack Martin to roll over him. The results of an MRI exam have not been released by the Cowboys, but a report on the team website says Lee has been told he has a torn anterior cruciate ligament.

If Lee is out for the season, that would mean the defense that ranked last overall in the league a year ago will be without its top two players. Franchise sacks leader DeMarcus Ware was released earlier in the off-season.

Then again, the Cowboys might be used to playing without the oft-injured Lee, who missed five of the final six games last year with hamstring and neck injuries. He has missed 18 games since entering the NFL in 2010, but also leads the league at his position with 11 interceptions during that time period.

The six-year extension he signed last year is worth up to $51 million but has durability-based incentives built in. It's already looking likely he'll miss out on a bonus in 2015 for not playing enough snaps in 2013 and 2014.